command line tool exposing lexical-scope

npm install scoped
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scoped is a command line tool to help you reason about your javascript.

scoped is also a library that will give you all of the scope information about a given falafel-generated AST! (it even works with let!)

var scoped = require('scoped')
  , falafel = require('falafel')

falafel('<some javascript>', scoped(function(scope) {
    scope.vars                          // vars declared in this scope
    scope.vars[0].name                  // the name of the var
    scope.vars[0].nodes                 // a list of nodes + kinds of use
    scope.vars[0].nodes[0].kind         // "implicit", "explicit", or "declare"
    scope.vars[0].nodes[0].node         // the esprima AST node.

    scope.children                      // the list of child scopes of this node
    scope.children[0]                   // as an array.

    scope.uses                          // the list of variables that this scope
                                        // "uses" from parent scopes. at top level,
                                        // these are globals.

// you can also tell scoped to ignore certain globals:
falafel('<some javascript>', scoped(['Math', 'module'], function(scope) {


it notifies you of globals -- both explicit (created by assigning) and implicit (use without definition) -- and, when given a position in the file, will let you know what variables are in scope at that point.

example scoped output


scoped path/to/file.js

outputs only global usage/leakage information, with line and column numbers.

scoped path/to/file.js --position=line[,column]

outputs scope chain, with usage/definition for each scope. position is in the form LINE,COLUMN. ,COLUMN may be omitted, if so, it is assumed to be 1. Both line and column are assumed to be 1-indexed (like most editors).

  • Green + signs indicate scope definitions -- i.e., a new variable was created in this scope.

  • Purple * signs indicate use of a variable from a containing scope.

  • If the function is named, it will use that to describe the function.


npm install -g scoped



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